Spinal Stenosis: To Fuse or Not To Fuse?

MedMaven

Dec 7, 2019

David Borenstein MD, Executive Editor updated 11/2019

Spinal stenosis is a condition caused by too little room in the vertebral canal due to inflammation of the nerves from the spinal cord. When the nerve roots are compressed, the blood supply to the nerves is also indirectly compressed resulting in a set of symptoms called neurogenic claudication. These symptoms include pain, cramping, weakness, or tingling in the legs, lower back, or buttocks, and are chiefly precipitated by walking or prolonged standing. Today, spinal stenosis has reached almost epidemic numbers as a medical problem for the baby-boomer population, and the right course of action remains a matter of controversy in the medical realm.

For some people, non-surgical therapy with exercise and weight reduction can be helpful with decreasing the functional disability associated with spinal stenosis. However, this kind of therapy is not always adequate, and anyway, removing the pressure on the nerves through surgical means is the more widely recognized therapy for this condition.

But the question remains as to what the correct surgery is. The most common form of spinal operation for stenosis is a decompression procedure. During this type of surgery, pieces of bone are removed from the part of the vertebra that is pressing on a nerve. Most commonly the lamina (the flat, posterior portion of the vertebra) is removed. But sometimes, bone near the facet joints needs to be removed as part of the procedure. The risk is in removing too much bone, thereby resulting in more instability of the spine at the decompressed level and further increasing pain.

The other type of surgery involves fusion. Fusion operations use rods and screws to prevent movement between vertebral levels. For some individuals, there is no question about which type of surgery is right for them—fusion is the only choice. These individuals have confirmed instability in the spine as their spines move 3 millimeters or more on X-rays bending forward and backward.

The controversy exists regarding the use of fusion operations in individuals who do not have spinal instability and stenosis. One way of thinking is that by undergoing fusion at the time of decompression is that the operation itself has the potential to destabilize the spine. On the other hand, fusing the spine before it becomes unstable could prevent the spine from further decompression.

Two clinical trials, one from the USA and one from Sweden, reported on the differences in outcome for surgery for spinal stenosis with and without fusion. In the USA study, 66 patients with stenosis and a stable slippage of the spine (spondylolisthesis) were the same when measured by their improvement of disability. Overall physical function was benefitted by a minimal clinically important difference in the fusion group.

In the Swedish study, 247 patients with or without a stable spondylolisthesis underwent decompression with or without fusion. No significant difference regarding physical function or disability was reported. In both studies a greater cost and longer hospital stay was associated with fusion operations.

Of interest in both studies was the number of individuals who needed a second operation. About 21% and 34% on individuals with decompression alone in Sweden and the USA respectively needed a second operation. The corresponding numbers for the fusion group was 22% and 14% respectively.

BOTTOM LINE: Spinal stenosis patients should try all non-surgical therapies first before considering surgery. If surgery is required, a simple decompression operation is the best choice. The operation is associated with a shorter hospital stay, lower cost, and the same outcome as the more complicated fusion operation. A small, but significant number of surgical patients may require a second operation in the future.